Intel's Linux CPU Temperature Driver Being Adapted To Handle 128+ CPU Cores

[phoronix]

Phoronix: Intel's Linux CPU Temperature Driver Being Adapted To Handle 128+ CPU Cores

Intel's CPU temperature driver "coretemp" within the Linux kernel is being adapted so it can report CPU core temperatures in excess of 128 cores...

https://www.phoronix.com/news/Intel-Linux-CPU-Temp-128-Cores

[ThomasD]

"640K ought to be enough for anybody"

[bug77]

"640K ought to be enough for anybody"

Eh, let's be honest, as long as it handles all the current CPUs, that's good enough. As its limit approaches, the driver is improved. No harm, no foul.

[timofonic]

Six months later...

AMD releases a CPU with 512 powerful cores and other optimized for power efficiency.

[rene]

don't tell me Intel is also going to unprofessionally just glue CPU dies together like AMD, ...! :-/

[Anux]

don't tell me Intel is also going to unprofessionally just glue CPU dies together like AMD, ...! :-/

Even better, they are running a new campaign in the same veins: https://wccftech.com/intel-calls-out...ths-marketing/ despite them doing the exact same thing several times. Not to mention they have no standing against either AMD CPU and their new core extreme lineup is actually slower than their previous generation.
I guess this is just Intels way of saying they can't compete anymore. A little bit sad but also funny.

[schmidtbag]

We're reaching a point of core count and transistor density where I'm beginning to question whether it's really necessary to have a sensor for each core. In Intel's case, one E core is almost 1/4 the size of a single P core, yet, E cores inherently run cooler, so wouldn't one sensor for a cluster of 4 cores be sufficient?
None of this is to say the driver shouldn't be updated anyway, but I just don't think it's necessary to be measuring per-core temperatures in servers anymore. I do feel it is necessary for desktop CPUs since their high clock speeds means a lot of energy density in a small area that isn't necessarily climate controlled very well.

[Anux]

... I'm beginning to question whether it's really necessary to have a sensor for each core.

It is totally necessary, if you measure core 1 but load core 4 then core 1 will never show the real temp, probably 20 or more degree difference. That is what decides between BSOD and super high turbo boost.

If you mean showing this data to the end user, then even 1/4th is too much. Most users don't care about temps and those that do would probably be fine with one peak and one average value.
Only in very specific cases do you care about individual temps (overclocking etc.).

[schmidtbag]

It is totally necessary, if you measure core 1 but load core 4 then core 1 will never show the real temp, probably 20 or more degree difference. That is what decides between BSOD and super high turbo boost.

Remember: we're talking about E-cores in a server chip here. So, there wouldn't be any high boosting going on and the heat would be spread through the large surface area of the package. If one of these cores is to get too hot, chances are, the environment as a whole is too hot.
Like I said, for desktop chips (in particular, P-cores), having a sensor per core makes sense, for the reasons you mentioned.
But also like I said: E-cores are roughly 1/4 the size of a P-core. If your logic is that 1 sensor for 4 E-cores won't show you the real temp, why would 1 sensor be sufficient for a P-core? After all, you never really use 100% of a core's transistors at a time. Different sections are bound to get hotter than others. So, wouldn't that mean we should see multiple sensors per P core?

If you mean showing this data to the end user, then even 1/4th is too much. Most users don't care about temps and those that do would probably be fine with one peak and one average value.
Only in very specific cases do you care about individual temps (overclocking etc.).

Well, isn't the point of this driver for the user?

[Anux]

Remember: we're talking about E-cores in a server chip here. So, there wouldn't be any high boosting going on

They are still boosting just with more conservative thresholds.

and the heat would be spread through the large surface area of the package.

No, the heat per core is more or less instant while changes on the die take several seconds. With modern 5nm silicon one core is super small and the material is not fast enough to spread the heat. Your CPU would already have crashed if you did measure the neighbor core.

But also like I said: E-cores are roughly 1/4 the size of a P-core. If your logic is that 1 sensor for 4 E-cores won't show you the real temp, why would 1 sensor be sufficient for a P-core?

Valid question, the answer is, it's not sufficient. There are actually many sensors per core, see here for Zen 1 (it only increased afterwards): https://en.wikichip.org/wiki/amd/mic...ures/zen#Power What you see as a user is just the hotspot of all sensors in that area.

And yes it is more a sensor per area thing than a sensor per core thing.

Well, isn't the point of this driver for the user?

I don't think any server provider cares about individual core temps. It's more likely for drivers that control boosting/powermanagement etc.